The membrane interactions of the proteins of enveloped viruses will be investigated. These studies concentrate on 3 viruses that have structural features in common: influenza virus, Sendai virus (a parainfluenza virus), and vesicular stomatitis virus (a rhabdovirus). Of particular interest are the interactions occurring on the cytoplasmic surface of the host plasma membrane. There are three primary areas of investigation. The first area is the membrane interactions involved in virus maturation, which occurs by budding from the host plasma membrane. Immunofluorescence and immunoelectron microscopy will be used to visualize the association of internal viral components with the cytoplasmic surface of the plasma membrane. Temperature sensitive virus mutants will be used to study the timing and sequence of association of internal viral components with the membrane following a shift from the non-permissive to the permissive temperature. The second area of investigation is the fate of internal viral components following virus penetration into host cells, which occurs by fusion of the virus envelope with cellular membranes. The influence of viral membrane proteins on the initial biosynthetic events in virus replication (synthesis of viral mRNA) will be investigated. Finally, the structural interactions of isolated viral components reconstituted into model structures such as liposomes will be investigated. These studies will use biophysical techniques such as resonance energy transfer between fluorescent-labeled proteins and lipids. These projects should provide basic biochemical and structural information about virus assembly and dissembly (following penetration). The results should be relevant to the replication of a wide variety of enveloped viruses in addition to the individual ones being studied. In addition, viral proteins serve as models for host proteins that perform similar functions, so that our studies may provide a more general model for the interaction of ribonucleoproteins with membranes, and the interaction of integral and peripheral membrane proteins with each other.